package com.lms.dao;


import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

//操作数据库的公共类
public class BaseDao {
    private static String driver;
    private static String url;
    private static String user;
    private static String pwd;

    static {
        Properties properties = new Properties();
        InputStream resourceAsStream = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
        try {
            properties.load(resourceAsStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
        driver=properties.getProperty("driver");
        url=properties.getProperty("url");
        user=properties.getProperty("username");
        pwd=properties.getProperty("password");
    }

    public static Connection getConnection(){
        Connection connection=null;
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url,user,pwd);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return connection;
    }
    //查询
    public static ResultSet execute(Connection connection,
                                    PreparedStatement preparedStatement,ResultSet resultSet,
                                    String sql,Object[] params) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i+1,params[i]);
        }
        resultSet = preparedStatement.executeQuery();
        return resultSet;
    }
    //更新
    public static int execute(Connection connection,PreparedStatement preparedStatement,
                              String sql,Object[] params) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i+1,params[i]);
        }
       return preparedStatement.executeUpdate();
    }
    //关闭连接
    public static boolean closeResource(Connection connection,PreparedStatement preparedStatement,
                                        ResultSet resultSet){
        boolean flag=true;
        if (connection!=null){
            try {
                connection.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag=false;
            }
            connection=null;
        }
        if (preparedStatement!=null){
            try {
                preparedStatement.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag=false;
            }
            preparedStatement=null;
        }
        if (resultSet!=null){
            try {
                resultSet.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag=false;
            }
            resultSet=null;
        }
        return flag;
    }
}
